1. Field of Invention
The invention relates to a method for air conditioning a room.
2. Description of the Prior Art
It is desirable to set a comfortable climate within rooms, i.e., to attain an environmental condition in which the thermal, physical and hygienic parameters are within limits, which lead to no or only statistically minor objections, and which are even felt extremely pleasant. The desired comfortable room climate is mainly brought about by air conditioning and ventilation systems.
Equipment conditioning the room climate as regards to temperature and humidity are normally known as air conditioning systems. Another factor influencing the room climate is the pollutant dilution with respect to the removal of anthropogenic CO2, together with other pollutants, such as odors, air-foreign substances, etc. In addition, water or water vapor must be removed as a result of respiration, perspiration, etc. There must also generally be a removal of heat from the room as a result of heat transmission by human or mechanical heat sources therein.
The removal of these heat, humidity and pollutant loads or charges is compensated by conditioned supply air in the room in order to maintain a sought room air state. Particularly, the desired removal of pollutants requires the supply of cleaner air, which is generally taken from the environment in the form of so-called external air, and whose quantity is determined by the internal air concentration increase as a function of the concentration in the external air.
Hitherto, this external air supply has been obtained using air treatment systems (hereinafter called xe2x80x9cair conditioning systemsxe2x80x9d), which ensure a clearly defined room air state as a result of the supply of external air, the removal of room air, as well as by cooling and heating external and/or room air.
German patent no. DE 36 10 069 A1 discloses a method for air conditioning a room, which is determined by the actual values heat load, humidity load and carbon dioxide load, and the desired values temperature, humidity and carbon dioxide concentration, in which the external air is cooled to a saturation temperature and, consequently, dehumidified.
It is also known from Recknagel, Sprenger Schramek, Taschenbuch fur Heizung und Klimatechnik, Oldenburg, 1999, pp 310-312, 325, and 327, to regulate the room climate towards the carbon concentration.
The problem of the present invention is to provide a method for the air conditioning of a room involving limited apparatus costs and limited energy costs, which with regards to its hygienic quality, particularly the carbon dioxide concentration, is improved compared with existing air conditioning systems.
According to the invention, this problem is solved by the features of claim 1, whilst advantageous developments of the invention are given in the subclaims.
The invention is based on the consideration that is exclusively the supplied external air is cooled, with regards to the temperature and atmospheric humidity, it is possible to obtain a desired and comfortable value to which is supplied feed air precisely defined in its state. The heat load can be given as ah in kJ/kg and the humidity load as xcex94x in gram water/kg of dry air in the h,x diagram, said values being representable as distances in the h,x diagram. The supply air state must be so chosen with regards to temperature and atmospheric humidity that it can absorb the heat load xcex94h and the humidity load xcex94x. The mixing point of supply air and room air (hereinafter called xe2x80x9cmixed airxe2x80x9d) must consequently, starting from the room air, be lower by xcex94h and xcex94x.
With regards to the atmospheric humidity, the supply air state is fixed in such a way that it is saturated with water vapor. Thus, if an interconnection takes place in the diagram of the room air state point and the mixed air, then a mixing line is obtained, whose intersection with the saturation line corresponds to the humid air state (hereinafter called xe2x80x9csupply airxe2x80x9d state). As the h,x diagram only gives intense quantities, the supply air quantity (as a mass or volume flow in kg or m3 per time unit) must be separately calculated. The supply air quantity is higher than corresponds to the standard hygienic rules concerning the carbon dioxide content. Therefore, the room air is not only at the desired temperature and atmospheric humidity value, but also has a lower carbon dioxide content and is, consequently, more hygienic.
Such a method has not hitherto been used in the prior, and in fact, in.conventional air conditioning systems re-circulated air or mixed air, i.e., re-circulated air and the necessary external air, are dehumidified by cooling to such an extent that as supply air they can absorb the humidity load. However, such a low air temperature is reached that it is necessary to reheat the air. This reheating requires additional apparatus costs, which in turn, leads to unnecessary energy costs.
A cooling of exclusively external air to a low temperature, according to the invention, has hitherto been subject to the objection that it required particularly expensive, special cooling methods, which increase the apparatus and energy costs to such an extent that the apparatus and energy costs caused by reheating appeared more favorable.
However, according to the invention, through the use of a pumpable ice/liquid mixture, the possibility is created of attaining a random state point of the air in the h,x diagram, while bringing about the additional advantage of a small heat exchanger surface.
It is also advantageous that an external air flow is subdivided into two air flows after passing through a valve. Optionally, fans can be provided for promoting said air flows. Only a partial flow is cooled in a heat exchanger to such an extent that it can be mixed in a mixing chamber with the first partial flow and the temperature after passing through the heat exchanger, and the partial flow ratio between the partial flows is chosen in such a way that the so-called mist or fog region is attained in the mixing chamber.
In the mixture is formed a mist, which separates with a device the water in a removal line. Another removal line already exists in the cooling device.
The device dehumidifying the mist can operate e.g. by means of capillary forces as a wick or fibre mat or using so-called demisters (regularly or irregularly), devices made from metal, plastic or knitted fabric and which are also known as xe2x80x9cdemister candlesxe2x80x9d. Thus, only a small volume flow has to pass via a heat exchanger, and consequently, the latter can be manufactured with a smaller surface area than would be the case if the entire air flow was passed through the same.
There is no longer a need to heat one of the partial flows following the separation of water, as has previously been the case.
The further desired cooling is achieved in an energy-favorable manner, if as the cold supply of the air cooler use is made of a cooling agent of pumpable, liquid slush ice which is, in any case, produced at temperatures below the freezing point of water, and here brings about a pronounced air cooling so that a larger air flow can be supplied in an un-cooled direct manner for dehumidification. Such a slush ice can be stored, and consequently, requires a reduced installed capacity.
The introduction of supply air into the room should not take place in unmixed form, because the cold dry air gives rise to an unpleasant feeling for persons in the room. It is more particularly proposed that the treated air be allowed to enter a nozzle through a regulating valve, and is introduced in mixed air form into the room.
A conical sleeve, displaceable with respect to the nozzle along the extension thereof, permits the induction of room air. A further air jet outside and along the sleeve is mixed with the induced air and forms an air jet, whose volume and temperature are controlled, but which essentially corresponds to the room temperature.
Upstream of the nozzle is provided a valve, whose adjustment and fixing of the displacement of the sleeve permits determination of the introduced volume, as well as the nature and quantity of induced room air so that desired room air conditions are obtained in a residence zone.
Preferably, the introduction nozzles are fitted to the ceiling of the room, and in the room the entrance doors can have a so-called air shower so that persons entering the room in a highly heated state rapidly become accustomed to a cooler room climate, because at some distance from the door there is greater mixing with the room air. Simultaneously, the known door effects, namely the introduction of warm air, can be prevented by such an air shower. Optionally, both the supply-regulating valve and the adjustable cone displacement can be remotely controlled.
To maintain the necessary dehumidification, it was hitherto necessary to cool all the supplied air to below the dew point, allow water vapor to condense, and then re-warm the air. However, this requires much more energy.
In a h,x diagram (Mollier diagram), the mixing line should run between the point of desired room air state (characterized by the air pressure, room air temperature and humidity), and the point of the air state of the external air cooled to percentage humidity. A gradient is obtained, which is described by q/xcex94x, q being the heat load in kJ/kg and xcex94x the humidity load in gram H2O/kg of dry air.